The unit displays values in one of two modes which can be changed during
operation. The micro mode displays values in uHy, mHy, pF, and uF when
applicable. In this mode, for example, 10.00 nano-Farads displays as .01000
micro-Farads and 1 nano-Henry displays as .001 micro-Hy. It is for old timers like
me and is the way many parts are marked. The nano mode is for those more
metrically inclined. Table 1 shows how each range is displayed in each mode.

INDUCTANCE

nano mode

INDUCTANCE

micro mode

CAPACITANCE

nano mode

CAPACITANCE

micro mode

000-999 nHy

0.000 - 0.999 mHy

0.00 - 0.99 pF

0.00 - 0.99 pF

1.000 - 9.999 mHy

1.000 - 9.999 mHy

1.00 - 9.99 pF

1.00 - 9.99 pF

10.00 - 99.99 mHy

10.00 - 99.99 mHy

10.00 - 99.99 pF

10.00 - 99.99 pF

100.0 - 999.9 mHy

100.0 - 999.9 mHy

100.0 - 999.9 pF

100.0 - 999.9 pF

1.000 - 1.999 mHy

1.000 - 1.999 mHy

1.000 - 9.999 nF

1000 - 9999 pF

10.00 - 99.99 mHy

10.00 - 99.99 mHy

10.00 - 99.99 nF

.01000 - .09999 mF

100.0 - 150.0 mHy *

100.0 - 150.0 mHy *

100.0 - 999.9 nF

.1000 - .9999 mFd

1.000 - 1.500 mFd *

1.000 - 1.500 mFd *

TABLE 1. Display Options (* Some values may be out of range).

Operating Modes

When the Lx and Cx switches are off pressing the ZERO button sequences L/C Meter IIB
through five different operating modes.

READY MEASURE n
measures Lx or Cx and displays the result in nano mode

ie: Lx = 99 nHy, Cx = 12.34 nF

READY MEASURE u
measures Lx or Cx and displays the result in micro mode

id: Lx = .099 uHy, Cx = .01234 uF

READY MATCHnMODE first measures a reference component Lz or Cz
and displays the value in nano mode. When the ZERO button is pressed this
value is stored in RAM and the difference between it and subsequent components is
displayed in nano mode

ie: Lx - Lz = 99 nHy, Cx - Cz = 12.34 nF

READY MATCHuMODE first measures a reference component Lz or Cz and
displays the value in micro mode. When the ZERO button is pressed this value
is stored in RAM and the difference between it and subsequent components is displayed in
micro mode

ie: Lx - Lz = .099 uHy, Cx - Cz = .01234 uF

READY MATCH%MODE first measures a reference component Lz or Cz and displays
the value in nano mode. When the ZERO button is pressed this value is stored
in RAM and the ratio of the difference between it and subsequent components is displayed
in percent.

ie: (Lx - Lz)/Lz*100 =12.34%, (Cx - Cz)/Cz*100 = 12.34%

Note that a positive reading in the matching modes
means Lx is greater than Lz or Cx is greater than Cz and visa versa.

L/C Meter II is intended to measure inductors and
capacitors "out of the circuit".Inductors must
have a reasonable Q for their value and negligible distributed capacitance for their
value. I have tested it using commercially available RF chokes ranging from 0.1
micro-Henry to 1000 mico-Henry , Hash chokes up to 100 mico-Henry wound on ferrite rods,
on Pi-wound RF chokes up to 7.5 milli-Henry, on toroid wound inductors up to 150
milli-Henry (such as the HI-Q series obtainable from Mouser Electronics), and on several
slug tuned inductors from a Coilcraft Slot-10 designers kit (similar to the TOKO line of
tunable inductors).

Stray Inductance and Capacitance

The circuit traces on the PCB, the switches , and the test leads all contribute a small
amount of "Stray" inductance (Ls) and capacitance (Cs). These stray values
add to the values of Lx or Cx. The unit is zeroed by pressing the ZERO switch which
causes the unit to store the values of stray inductance or capacitance and subtracts them
from the measured values.

To zero Ls the operator must short circuit the test leads, press Lx and then press the
ZERO button. Similarly, for capacitors, the operator open circuits the test leads,
presses Cx and then presses ZERO.

The stored values of Ls and Cs are saved until the operating mode is changed. When
measuring components, it is not necessary to re-ZERO between components. When the
operating mode is changed from MEASURE to MATCH these values are reset to zero.

If an inductor is inserted when the Cx switch is depressed it will display NOT A
CAPACITOR. This does not work for very large values of Lx and the unit may
display an erroneous reading.

Putting a capacitor in when the Lx switch is pressed displays
NOT AN INDUCTOR. This is not true for very large values of Cx in which
case the unit may display an erroneous reading.

L/C Meter IIB can zero out ANY value in its range. If a value is inserted
and ZEROd the unit will display the difference between it and subsequent components
similar to the MATCHnMODE and MATCHuMODEs. The difference in the MATCHxMODEs is that
the range is frozen to the resolution of the initial component. This limits the minimum
difference in values to be 1 part in 10,000 or .01%. The reason for this may not be
obvious. The maximum resolution of the unit is four digits at the value of the
components being measured. Consider two components, one with an exact value of
5000 pF and the other with an exact value of 5010.25 pF. The difference would be
10.25 pF, however the unit cannot resolve less than 1 pF at this range and it would be
misleading to display the fractional portion of the difference.

Construction (There is a layout drawing on last page
in case you cannot read the pictures)

NOTE: there is only 3/8 inch space under the display,
leave enough lead length to tip regulator and two electrolytics at an angle so that the
vertical dimension does not exceed 3/8 inch.

CLICK ON ANY IMAGE TO ENLARGE

Begin by installing the resistors.

Then the IC sockets

When soldering the sockets, support the
corner

Using the black foam the ICs are shipped on.

If you received a 14 pin connector install it in
pins 1-14

of the PCB. The 16 pin shown is the current
production.

Installthe connector with
the guard toward

the bottom of the PCB

Install the small switch.

Solder just one pin

Check to make sure the switch is seated squarely on the
plastic tabs then solder remaining pins.

Install the remaining three switches.

Install the voltage regulator flat side toward right

Install the three 10uF electrolytics with polarity as shown above. Do not
try to mount flush to PCB. Incorrect pad spacing is intentional so they can be tipped
under display module

Note the long lead on these parts is the positive lead.

Install the switch knobs by pushing them onto the square switch ends.

Install the two 0.1uF ceramics, the 2.2pF ceramic and

the two 20 to 27pF (value not critical) ceramics

Install the 680pF ceramic, 10uF tantalum (long lead positive). C2a and b
are in a little brown envelope.

L1 installation.

I don't know why but best results are
obtained if the terminal connected to the outer layer is toward the bottom of the pcb.

carefull inspection will reveal that the
other

lead clearly goes to a buried layer.

Install C2a and C2b and L1 (68uHy)

Install contrast control and initially set
fully CCW.

Install the crystal between the two 22pf
caps.

Install the relay with printing toward the LM311 socket as shown. The relay
has an internal diode so it has a polarity.

Install the two spacers using #8 washer and screw from the
bottom of the pcb

Install the female header connector on the display module.

If you received a 14 pin connector, use pins 1-14.

For 16 pin connector use all pads.

For 14 pin connector use pads 1-14.

Solder only one pin, check to make sure connector is at right angle then
solder remaining pins.

Take the cover off the enclosure battery box and thread the battery wires
through the cutout as shown above

Insert those wires into the PCB as shown above and solder on the
back side. At this point you can test the unit by attaching a 9 volt battery and
tuning the unit on. You should see the power up sequence described in the text
above.

Install the unit in the enclosure using the three #4 sheet
metal screws.

Put the front cover on the enclosure. Disassemble the test jacks as
shown above and discard the parts circled.

Reassemble the remaining parts and hand screw them into the threaded
spacers visible through the holes in the enclosure. Then put on the
knurled parts but do not

over tighten.

Assembling the optional
SMD probe is a bit of a no brainer. Just remember to clip the plastic part at the tips
even with the metal part using a finger nail clipper as shown above in upper right.

The
kit of parts is shown on the top and the finished product and how to use it on the bottom.

Put the four #2 sheet metal screws into the back to secure the enclosure.

Turn the unit on and enjoy the fruits of your labor.

The unit will display "L/C Meter IIB" for 10 seconds followed by
"CALIBRATING" for two seconds followed by "READY MEASURE x". If
so, your up and running. Adjust the contrast control so the background is just
barely visible. Test leads should not exceed 4 inches in length with a banana
plug at one end and alligator clip at the other.

Troubleshooting

It is very unlikely you will have any problems,
however, if you just cant seem to get it to work I will try to fix it free except
for a $4.00 return postage and handling fee.

If it did not work, remove the PCB and carefully inspect to see you have soldered
everything that should be soldered and have not soldered anything that should not be (look
for solder bridges). Bad soldering accounts for 99% of units that fail to work
immediately. Here are some hints on where to look.

1) Blank display, contrast control not adjusted
correctly. Start with it fully counter clockwise. This is the number one
problem I get calls on.

2) On rare occasions a through-hole plating may not have
gone through from the bottom to the top of the PCB.Check
those few pads on the top side that have circuit traces and solder the component lead on
the top side of the PCB as well as the bottom.

3) Blank display, check 5V power to CPU and display.
If you ever applied reverse voltage, even for a moment, or if you installed the PIC16C622
in backwards you have blown the 78L05 voltage regulator. Surprisingly, the PIC
usually survives.

5) Displays WAIT, then CALIBRATING and sticks in CALIBRATING.
Oscillator (LM311) is not oscillating. Check soldering around LM311, LM311
properly installed, parts properly installed. C3 in backwards?(see note 6). Also
theZERO button may be stuck in or not soldered. Check continuity to
ground from pin 13 of the CPU.

6) Seems to work but readings appear way off from components marked
value. Calibration capacitors not
correctly installed (you put some other part where they are supposed to go), C3
installed backward (+ terminal toward top, display end of the PCB), or relay in
backwards (relay should be installed with its part number opposite the switches
and towards the LM311).

Operation

The typical stray inductance is .04 to .06 mHy's and the typical stray capacitance
is 5 to 7 pF's. When measuring inductors less than 5 mHy's or capacitance's less
than 50 pF's it is advisable to ZERO the unit first. For larger values the strays
are insignificant to the result. It is difficult to retain a reading of 0.000 pF's
because of the extreme sensitivity of the unit. Your body capacitance influences the
reading. Try ZEROing the capacitance and then move your hands around the test leads
without touching them. You will find your can adjust the reading a few hundredths of
a pF.

To measure inductance place the unknown across the test leads and depress Lx. To measure
capacitance place the unknown across the test leads and press Cx.

The oscillator tends to drift a few Hertz during the first few minutes of
operation. When measuring very small values the unit should be allowed to warm up
for about five minutes. With a resolution of 5 Hz, thermal drift will always occur
as evidenced by a slowly drifting reading. The first readings after pressing Lx or
Cx are the most accurate.

Accuracy and Resolution

L/C Meter IIB has four digit resolution which for small values of L and C are 1 nHy and
.01 pF. You cannot accurately measure values this small. The resolution
greatly exceeds the accuracy. You can measure values as small as .01mHy and .1 pF with about 15%
accuracy. You generally won't find components this small. For example a piece
of wire less than one inch long is .01 mHy.
The resolution is, however, relative and can be used for sorting a batch of similar
components as it truly does indicate which are slightly larger of smaller than
others. Also, for small values of inductance, the leads will contribute quite a bit
to the value. Measuring from the ends of the leads instead of next to the body of
the component can add up to .025mHy.

For small values the frequency of operation (test
frequency) is about 750 KHz decreasing to about 60 KHz at .1 mFd's
or 10 mHy's and about 20 KHz at 1 mFd or 100 mHy's.